(1) Field of the Invention
The present invention generally relates to a lighting module, and particularly to a direct-typed backlight module for a liquid crystal display panel.
(2) Description of the Prior Art
Liquid Crystal Display panel (LCD panel) itself is not able to generate light. In order to present images, a backlight source is typically therefore needed. Various different types of backlight modules have already been disclosed and used practically. However, LCD product having a diagonal screen size larger than 20 inches often adopts a “direct-typed backlight module” as its backlight source. Within the direct-typed backlight module, light is actually generated from lamps, such as lamp tubes or U-shaped lamps respectively shown in FIG. 1 and FIG. 2. Alternatively, snake-shaped lamps, which are not shown in figures, are also adopted in prior arts.
Please refer to FIG. 1. A direct-typed backlight module 10 comprises a bezel 12 and a plurality of lamp tube 14. Typically, the lamp tube 14 is very thin and is fixed on the bezel 12 by utilizing some fixing component. Considering the structure of the lamp tube 14 shown in FIG. 1, two fixing components 16 are respectively disposed to support and fix the two ends of one lamp tube 14. As shown in FIG. 1A, which shows the lamp tube 14, the bezel 12 and the fixing component 16 of FIG. 1 on an enlarged scale, the fixing component 16 is designed as a C-shaped ring for facilitating installing the lamp tube 14.
Besides the lamp tube 14 having a straight structure shown in FIG. 1, other bending structures are also used in prior arts. For example, the U-shaped lamp 24 shown in FIG. 2 has a structure comprising one bending portion. Adopting lamp of bending structure generally has the advantage of reducing the amount of lamp electrode. However, the two ends of the U-shaped lamp 24 are located at the same side of the bezel 12. Specific fixing component is needed to fix the bending portion of the U-shaped lamp 24 on the bezel 12.
O-ring 18 is a typical fixing component for the bending portion of the U-shaped lamp 24. The O-ring 18 rings the U-shaped lamp 24 at the bending portion. However, the O-ring 18 is substantially made of plastic materials, such as rubber. It contacts with the U-shaped lamp 24 and has a function as a heat sink. After the backlight module 20 is operated for a while, the portion of the U-shaped lamp 24 coved by the O-ring 18 has a temperature lower than the other portions. Occasionally, the relative low temperature would result in a “pink phenomenon”, which means that pink light is generated at this relative low temperature area and defeats the optical quality of the backlight module 24.
To resolve this drawback, a prior art disclosed in the U.S. Pat. No. 6,722,773 has provided a fixing component shown in FIG. 3A and FIG. 3B. FIG. 3A is a perspective view of the U-shaped lamps and the fixing component. FIG. 3B is a cross-sectional view taken along line 3b-3b of FIG. 3A. This prior art generally utilizes the hook structures 162 shown in FIG. 3A and FIG. 3B to support and fix the U-shaped lamp 24. An individual hook structure 162 has a relatively less contact area with the U-shaped lamp 24 than the O-ring 18 of FIG. 2. Because the contact area is reduced, the heat sink ability of the hook structure 24 is not as remarkable as the O-ring 18. The mentioned “pink phenomenon” is somehow resolved. However, also because of the reduced contact area, the fixing ability of the hook structure 162 is not so firm as the O-ring 18. Therefore, these fixing components have to be arranged as FIG. 3A. Obviously, required amount of the fixing components has to increase. And it also results in a complicated assemble process.
As the screen size of liquid crystal display panel keep enlarging, requirement according to the safety approvals becomes much more restricted. Accordingly, some fixing components according to prior arts are not able to conform the standards. Hence, to provide fixing component with reliable fixing ability and without the mentioned drawback of pink phenomenon is an important issue to these art.